org.apache.hadoop.hbase.zookeeper

Class MetaTableLocator

java.lang.Object

org.apache.hadoop.hbase.zookeeper.MetaTableLocator

@InterfaceAudience.Private
public class MetaTableLocator
extends Object

Utility class to perform operation (get/wait for/verify/set/delete) on znode in ZooKeeper which keeps hbase:meta region server location. Stateless class with a bunch of static methods. Doesn't manage resources passed in (e.g. HConnection, ZooKeeperWatcher etc). Meta region location is set by RegionServerServices. This class doesn't use ZK watchers, rather accesses ZK directly. This class it stateless. The only reason it's not made a non-instantiable util class with a collection of static methods is that it'd be rather hard to mock properly in tests. TODO: rewrite using RPC calls to master to find out about hbase:meta.

Constructor Summary

Constructors

Constructor and Description
MetaTableLocator()

Method Summary

Methods

Modifier and Type	Method and Description
ServerName	blockUntilAvailable(ZooKeeperWatcher zkw, long timeout) Wait until the meta region is available and is not in transition.
void	deleteMetaLocation(ZooKeeperWatcher zookeeper) Deletes the location of hbase:meta in ZooKeeper.
ServerName	getMetaRegionLocation(ZooKeeperWatcher zkw) Gets the meta region location, if available.
List<HRegionInfo>	getMetaRegions(ZooKeeperWatcher zkw)
List<Pair<HRegionInfo,ServerName>>	getMetaRegionsAndLocations(ZooKeeperWatcher zkw)
static RegionState	getMetaRegionState(ZooKeeperWatcher zkw) Load the meta region state from the meta server ZNode.
boolean	isLocationAvailable(ZooKeeperWatcher zkw) Checks if the meta region location is available.
static void	setMetaLocation(ZooKeeperWatcher zookeeper, ServerName serverName, RegionState.State state) Sets the location of hbase:meta in ZooKeeper to the specified server address.
void	stop() Stop working.
boolean	verifyMetaRegionLocation(HConnection hConnection, ZooKeeperWatcher zkw, long timeout) Verify hbase:meta is deployed and accessible.
void	waitMetaRegionLocation(ZooKeeperWatcher zkw) Waits indefinitely for availability of hbase:meta.
ServerName	waitMetaRegionLocation(ZooKeeperWatcher zkw, long timeout) Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MetaTableLocator

public MetaTableLocator()

Method Detail

isLocationAvailable

public boolean isLocationAvailable(ZooKeeperWatcher zkw)

Checks if the meta region location is available.

Returns:

true if meta region location is available, false if not

getMetaRegionsAndLocations

public List<Pair<HRegionInfo,ServerName>> getMetaRegionsAndLocations(ZooKeeperWatcher zkw)

Parameters:

zkw - ZooKeeper watcher to be used

Returns:

meta table regions and their locations.

getMetaRegions

public List<HRegionInfo> getMetaRegions(ZooKeeperWatcher zkw)

Parameters:

zkw - ZooKeeper watcher to be used

Returns:

List of meta regions

getMetaRegionLocation

@Nullable
public ServerName getMetaRegionLocation(ZooKeeperWatcher zkw)

Gets the meta region location, if available. Does not block.

Parameters:

zkw - zookeeper connection to use

Returns:

server name or null if we failed to get the data.

waitMetaRegionLocation

public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw,
                                long timeout)
                                  throws InterruptedException,
                                         NotAllMetaRegionsOnlineException

Gets the meta region location, if available, and waits for up to the specified timeout if not immediately available. Given the zookeeper notification could be delayed, we will try to get the latest data.

Parameters:

timeout - maximum time to wait, in millis

Returns:

server name for server hosting meta region formatted as per ServerName, or null if none available

Throws:

InterruptedException - if interrupted while waiting

NotAllMetaRegionsOnlineException

waitMetaRegionLocation

public void waitMetaRegionLocation(ZooKeeperWatcher zkw)
                            throws InterruptedException

Waits indefinitely for availability of hbase:meta. Used during cluster startup. Does not verify meta, just that something has been set up in zk.

Throws:

InterruptedException - if interrupted while waiting

See Also:

waitMetaRegionLocation(org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher, long)

verifyMetaRegionLocation

public boolean verifyMetaRegionLocation(HConnection hConnection,
                               ZooKeeperWatcher zkw,
                               long timeout)
                                 throws InterruptedException,
                                        IOException

Verify hbase:meta is deployed and accessible.

Parameters:

timeout - How long to wait on zk for meta address (passed through to the internal call to getMetaServerConnection(org.apache.hadoop.hbase.client.HConnection, org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher, long).

Returns:

True if the hbase:meta location is healthy.

Throws:

IOException

InterruptedException

setMetaLocation

public static void setMetaLocation(ZooKeeperWatcher zookeeper,
                   ServerName serverName,
                   RegionState.State state)
                            throws org.apache.zookeeper.KeeperException

Sets the location of hbase:meta in ZooKeeper to the specified server address.

Parameters:

zookeeper - zookeeper reference

serverName - The server hosting hbase:meta

state - The region transition state

Throws:

org.apache.zookeeper.KeeperException - unexpected zookeeper exception

getMetaRegionState

public static RegionState getMetaRegionState(ZooKeeperWatcher zkw)
                                      throws org.apache.zookeeper.KeeperException

Load the meta region state from the meta server ZNode.

Throws:

org.apache.zookeeper.KeeperException

deleteMetaLocation

public void deleteMetaLocation(ZooKeeperWatcher zookeeper)
                        throws org.apache.zookeeper.KeeperException

Deletes the location of hbase:meta in ZooKeeper.

Parameters:

zookeeper - zookeeper reference

Throws:

org.apache.zookeeper.KeeperException - unexpected zookeeper exception

blockUntilAvailable

public ServerName blockUntilAvailable(ZooKeeperWatcher zkw,
                             long timeout)
                               throws InterruptedException

Wait until the meta region is available and is not in transition.

Parameters:

zkw - zookeeper connection to use

timeout - maximum time to wait, in millis

Returns:

ServerName or null if we timed out.

Throws:

InterruptedException

stop

public void stop()

Stop working. Interrupts any ongoing waits.